1. Technical Field
The present invention generally relates to semiconductor devices and methods of increasing feature density in fabricating semiconductor devices. More particularly, the invention relates to double patterning by creating a temporary mask of triangular sidewall spacers.
2. Background Information
In fabricating integrated circuits (ICs) or semiconductor devices, the density of components continues to increase to achieve greater functionality and reduced manufacturing costs. One such technique, commonly known as double patterning technique, has been developed to increase the feature density than what is currently possible with standard lithographic techniques. Two principle approaches utilized in the double patterning technique are double exposure and sidewall image transfer.
In the double exposure approach, the substrate is exposed using standard lithographic pattern and etch techniques either simultaneously or alternately, in a series of steps, to increase the feature density. In the more preferred, sidewall image transfer (SIT) approach, however, lithography is used as a starting point to pattern lines, followed by materials processing to produce smaller, narrower lines, thus avoiding the fundamental physical limits of resolution. In the SIT approach, a film on the sidewall of a line structure, referred to in that art as a mandrel, is used as the template from which to pattern the structure underneath it. When the mandrel is removed, the sidewall remains, and performs a function equivalent to what photoresist does for patterning underlying substrates. The SIT approach is sometimes referred to as a self-aligned double patterning (SADP) process, due to the doubling of the number of lined structures from the number of mandrels.
However, the current SADP approaches are cost prohibitive, particularly as a result of processes employed for the spacer deposition along with the increase in production cycle time due to the additional operations performed to pattern a particular layer. Furthermore, the current SADP approaches pose patterning difficulties due to the size of mandrels formed.
Hence, there continues to be a need for enhanced techniques to increase the feature density.